As a two liquid-type surface modifying agent which can be suitably used for a surface-modified substrate having desired properties such as hydrophilicity, hydrophobicity, lipophilicity and lipophobicity on its surface, there has been proposed a two liquid-type surface modifying agent composed of a I-type liquid containing an alkoxysilyl group-containing compound having a thiol group and a II-type liquid containing an (meth)acrylic compound (see, for example, Patent Literature 1). As a surface modifying agent having two properties which are contrary to each other, such as a combination of hydrophilicity and hydrophobicity or a combination of lipophilicity and lipophobicity, which can be fixed on a substrate, there has been proposed a two liquid-type surface modifying agent composed of I-type liquid containing an alkoxysilyl group-containing polymer and a silane coupling agent having a thiol group, and a II-type liquid containing an (meth)acrylic monomer (see, for example. Patent Literature 2). As a surface modifying agent which is hardly removed from a substrate even in contacting with water and is capable of forming a thin film having desired properties such as hydrophilicity and water repellency, there has been proposed a surface modifying agent containing a (meth)acrylic polymer having a specific repeating unit and an alkoxysilyl group at the position of at least one terminal (see, for example, Patent Literature 3).
The above-mentioned two liquid-type surface modifying agents can impart desired properties such as hydrophilicity, hydrophobicity, lipophilicity and oil repellency to the surface of a substrate. Therefore, the two liquid-type surface modifying agents have been expected to be applied to various uses such as a medical material, a biocompatible material and an optical material. In addition, the above-mentioned surface modifying agent forms a thin film having properties such as hydrophilicity, hydrophobicity, lipophilicity and lipophobicity. Therefore, the surface modifying agent has been expected to be applied to various uses such as a surface treatment agent for glass, a surface treatment agent for coating, a surface treatment agent for printing, a medical material, a biocompatible material, an optical material, a resin film and a resin sheet.
However, in recent years, there has been desired to develop a hydrophilic coating agent which can form a film comprehensively excellent in hydrophilicity, anti-fogging property, retention of anti-fogging property and water resistance as compared with a film formed by the above-mentioned two liquid-type surface modifying agents and the above-mentioned surface modifying agent.